Substituted acid amide antifoggants



Patented Feb. 12, 1946 4 UNITED STATES PATENT" ounce SUBSTITUTliD Acl lfmii ANTIFOGGANTS Q George E.

Rochester, N. Y.,

Company, Rochester, N. Y.,

New Jersey No Drawing.

Application January 13, 1944,

Serial No. 518,125

I 3 Claims.

This invention relates to log inhibitors for photographic emulsions and to photographic emulsions containing them.

It is known that photographic emulsions, par- I ticularly ultra-sensitive emulsions, exhibit a tendchemical iog, is formed in a number of ways. It

may be caused by the conditions under which the film or plate is stored, such as conditions of high temperature or unusuall long time of storage. The nature or the emulsion may also produce chemical fog, as well as the conditions of development of the emulsion, as by development for protracted periods of time or at temperatures above normal. Highly sensitive emulsions are more likely to fog than those of lower sensitivity. We are concerned primarily with general or chemical 08.

It is an object of the present invention to provide anti-fogging or tog inhibiting agents for ultra-sensitive photographic emulsions and thereby to preserve the emulsion against deterioration causing iog. A further object is to provide antiiogging agents which do not markedly lower the sensitivityoi the emulsion. Other objects will appear from the following description of my invention.

These objects are accomplished by developing an exposed silver halide emulsion in the presence of chioroacetamide or iormanilide, preferably by incorporating one of these compounds in the emulsion. These antiioggants may be incorporated inan emulsion particularly a fast negative emulsion, to which may be added optical sensitizing dyes. The emulsion may be one which is intended to be used directly after emulsiflcation or one which is subjected to ripening.

The compounds which we have found suitable for use as antitoggants in photographic emulto the required sions include chloroacetamide and tormanilide,

which have the following structure:

o1 cmo ONE. CIHlNIL-CHO Chloracetamidc Formanilide The antiioggant properties oi these compounds were tested as follows:

Silver iodobromide was precipitated in 0.8% gelatin-solution. Alter precipitation was complete this entire volume oiemulsion wascooled and divided into portions weighing 1643 grams each. To each portion was added enough gelatin to increase the gelatin concentration to approximately 6.6%. Each portion was then heated digestion temperature, that is, about C. and as soon as this temperature was reached a certain amount of the compound to be tested, e. g., 25 grams of o-chloracetamide, dissolved in 300 cc. of methyl alcohol, was added. Digestion was then continued for 30 minutes as the specified temperature and the emulsion was then chilled and stored in preparation (or shredding and washing. One orthese portions received no additions other than the required gelatin and it served as the control for all the portions originating from the same precipitation of silver halide.

' After washing, each emulsion was the optimum point for maximum speed and gamma with acceptable fog. Unsensitized and panchromatized samples or each emulsion so finished were coated by machine on glass plates. After the plates were dry, a series of sensitometric tats them. The data were then comoi' the check emulsion containtests include initial tests for speed, gamma and fog, made on the day after coating, similar tests plates incubated at F., dry heat, for 14 days and a third set of tests made on a third set of lates after having been kept under tropical conditions for 14 days. (The tropical conditions are simulated by varyinfl the temperature and humidity through a cycle to reproduce day and night conditions in tropical climates.) Plates for on a second set of each of these tests were developed for 3 minutes at 65 F.ln Kodak D-19 developer which had the following composition:

The results of these tests are tabulated below:

graphic emulsions. In addition to being useful in ordinary non-sensitized emulsions, they may be used in orthochromatic, panchromatic and X-ray emulsions. Various silver salts may be used as the sensitive salt such as silver bromide, silver chloride, silver bromiodide, and silver chlorobromide. The dispersing agent may be gelatin or other suitable colloid, such as collodion, albumen, cellulose organic derivatives or synthetic resins.

In addition to their use in the sensitive emul- Troplcal condition 14- Initial fog tests day inttugition log g fifg g Name oicompound Emulsion Emulsion Emulsion Emulsion Emulsion Emulsion with without with without with without compound compound compound compound compound compound Chloroacetamide 3.1 g. per liter .06 .06 .09 .14 .12 .20 Chloroacetamide 6.3 g. per ten. .05 .06 .07 .14 .12 .20 Ohioroacetamide 12.5 g. per liter; .05 06 .07 l4 10 Formanilide 12.5 g. per liter .04 03 17 36 14 22 The amount of fog was determined by reading the density of the unexposed area of the plate after exposure and development of the emulsion in the usual manner.

;The amount of the fog inhibiting agent used in the emulsion will depend upon the composition oi the agent and upon the type of emulsion In general, the amount of fog inhibiting agent used will vary from 1 gram to 15 grams per 1000 cc. of. wet emulsion. It will be understood that more or less than this amount however, if a greater amount is used in the emulsion, either no increased fog inhibiting effect is obtained or there is a decrease in the sensitivity may beused. Generally,

of the emulsion. These compounds may be in-.

corporated by mixing them with any suitable solvent which is inert with respect to the emulsion such as water, methyl alcohol, ethyl alcohol, acetone and others.

The fog inhibiting agents which we have descri ed may be used in various kinds of photosion itself, our fog inhibiting agents may also be emulsion which comprises developing said emulsion in the presence of a fog-inhibiting amount of chloroacetamide.

GEORGE E. FALLESEN.

JOHN A. LEERMAKERS. 

